钢管超声波测厚示值减小的原因分析

Analysis of Causes for Ultrasonic Gauge-measured Steel Pipe Thickness Value's being Less than Real value

在使用超声波测厚仪对钢管壁厚进行测量时,有时会出现示值小于钢管实际壁厚的情况,并且这些钢管内表面往往伴有许多鼓包和翘皮出现。对这种情况进行了分类统计,并取样进行分析。指出钢管超声波测厚示值减小是由分布在壁厚中间和靠近内表面区域的异常夹杂物引起的,内表面的鼓包和翘皮是由分布在壁厚靠近内表面边缘区域的异常夹杂物引起的;钢管内表面的翘皮与二辊斜轧穿孔变形产生的毛管内折有本质的区别。

When using an ultrasonic thickness gauge to measure the steel pipe,sometimes the indication values resulting from the testing are less than the real ones,and in such cases,the pipes being measured are always found to have inner bulges and fins.Classified statistics and sample analysis are made to such cases.As a result,it is identified that the problem concerning smaller indication values is caused by the nonmetallic inclusions as distributed in the middle wall area and the area close to the inner surface of the pipe,while the bulges and fins of the pipe are caused by the nonmetallic inclusions as held in the area just under the inner surface thereof.The said inner fin of the pipe is substantially different from the inner fold of the shell as occurring due to the deformation produced by the 2-roll rotary piercing process.